BIGCHEATER - God Mode
or
JUGGERNAUT
(Oddly, in some games it is BIGCHEATER, and in others it is JUGGERNAUT. Try both.)

NOCLIP - No Clipping mode (walk through walls)
or
WRAITH
(Same as God mode: sometimes it is one or the other)

FLY- Flying mode

Usually BIGCHEATER, NOCLIP, and FLY are together.
Usually JUGGERNAUT and WRAITH are together.

Thanks to Revolution readers Charlie Dykstra, Mike Geschke, Justin, and Tim Bo-Lassen!